Hello gents, it's been a while since I've had to come on here my 1996 850 is just too d@mn good of a car. Running like a champ with 300K miles on it.

I did however run into an issue yesterday when I had to have the emissions checked. All was well except for the NOx readings. The limits were 2.0 and she blew a 3.8....FAIL.

I understand that high readings are caused by high combustion temps from a lean fuel/air mixture. Any thoughts on what to check?

Just from my research I thought I would run some top end decarbonizer through it, clean the MAS, clean the EGR valve (if it has one, it doesn't appear to have one to me, is that possible?) change the oil, which is due any way and dump a new set of plugs in it.

It has been running great with no noticeable issues.

Any other thoughts?

Thanks in advance.

 

Have you run the codes yet? If you look under my posts you can read what I went through trying to get my car to pass the California emissions test. The biggest impact was replacing a bad OX sensor.

 

No I haven't run the codes. In fact I have never had to do that with this car. Is that something I can just go to an an Advance Auto or some place and have them pull them?

I never thought to do that in this case because the car hasn't "told" me anything was wrong. That's one of the things I love about it is it usually lets me know when something isn't right.

 

no check engine light? and look to see if your car is obd1 or obd2

 

If my understanding is correct, with his car being a '96, it should be ODBII. I may be wrong though, there may have been a switch over with Volvos in the '96 year.

 

It's OBD 2. No, no CEL which suprizes me. I typically get one when the wind is blowing the wrong way.

That's why I said above this car usually tells me when something isn't quite right. I'll pull the codes today and see if there is anything there.

If not, it could be the bone head techs at the emissions testing station, I have had to correct them in the past.

They had a notice in the waiting room that they had openings. The only qualifications were that you had to be breathing and be able to drive a manual T.

 

My car is a 95 but I had no check engine light and yet when I pulled codes it told me the OX sensor was bad.

 

Ok, a little more intel. I did all the steps I listed in my OP and tested today. (I also had the codes pulled, zero, nothing, nada.) Brought the readings down from a 3.8 to a 2.5. Need a 2.0 to pass. FAIL.

The state offers a free diagnostic that I took advantage of and this guy said he doesn't have an OEM scanner for this old of a Volvo and the generic scan doesn't tell the whole story.

Quote"Running lean most likely because it is open loop. Get into closed loop and then recheck LAMBDA with gas analyzer, make sure it is 1.000. It is running 1.03 to 1.05 LAMBDA at this time."

Thoughts? Vacume leak?

Did I mention this whole emissions thing is a total exercise in masturbation?

Thanks in advance for any additional clues.

 

I'm pretty thankful my state doesn't do emissions testing on vehicles. It seems like the entire process for a lot of states is exactly this.

 

I get the point of emissions testing, and it is a good thing, BUT it can sure be a pain in the rear. Read what I went through and you will see why I think that.